Home > EFSA publishes report on likely scenarios for spread of “Schmallenberg” virus in ruminants

The European Food Safety Authority (EFSA) has published a preliminary analysis of the likely scenarios on how a new virus, referred to as the “Schmallenberg” virus[1], could spread amongst animals in the coming months. This report, which was discussed by the Standing Committee on the Food Chain and Animal Health (SCOFCAH) on 7 February will help inform the European Commission and EU Member States regarding the current and possible future situation in the EU. The virus is assumed to belong to a vector-borne group of viruses transmitted by insects. The report highlights that further data are needed to monitor the presence of this recently reported virus and provides technical specifications for such data collection in all Member States.

The technical report from EFSA focuses on the animal health and welfare aspects of the newly found virus, highlighting that there are many uncertainties associated with it. The virus has been found in sheep, cattle and goats and has to date infected animals in Belgium, France, Germany, the Netherlands and the United Kingdom.

The virus is believed to be a part of the Simbu serogroup of viruses transmitted by midges and mosquitoes and therefore it is likely that the new virus is transmitted in the same way. However, the possibility of direct animal-to-animal transmission, although unlikely, cannot be excluded at this stage. In infected animals, the virus has currently been observed to cause fever, diarrhoea and reduced milk production for up to a week. If infection occurs in pregnant animals during a short, vulnerable stage of the pregnancy[2] it can result in severe birth defects of the offspring.

Based on the limited data available, the report provides epidemiological scenarios that could be observed in the coming months in Europe. The series of scenarios have been developed based on the hypothesis that the transmission mode and the vectors transmitting the virus are similar to that of Bluetongue[3]. The analysis concludes that the number of vectors and the temperature have an impact on the possible spread of the virus in a susceptible animal population. However, there is lack of data on many aspects, such as how likely animals are to become immune. This is important as scientific knowledge of related viruses indicates that animals can develop strong immunity following exposure to the virus which will have an impact on the way the virus can spread.

In order to assess the impact of the virus at EU level and its possible further spread, surveillance data are needed from all EU Member States. Based on its experience in assessing risks related to other animal- and vector-borne diseases, such as Bluetongue, EFSA will work together with Member States to ensure that the epidemiological data collected in the coming months provide an overview of the situation in Europe. Throughout this process, EFSA will regularly share reports on the status and analysis of the data collected.

A preliminary assessment by the European Centre for Disease Prevention and Control (ECDC) concludes that there is currently no evidence that the virus could cause illness in humans. As the genetically most related viruses[4] do not cause disease in humans, it is unlikely that this new virus will cause disease in humans but it cannot be excluded at this stage. EFSA continues to liaise with ECDC in order to closely monitor possible public health impact and will address areas of concern for human health, should these arise.

The European Commission has requested EFSA to provide urgent scientific and technical assistance for possible risks resulting from the virus. Based on data collected from Member States, EFSA will provide an overall assessment of the impact of the virus infection on animal health, animal production and animal welfare together with a state-of-the-art review on what is known about the virus by June 2012.

The information available on the new virus discovered in Europe in the second half of 2011 indicates that it is a part of the Simbu serogroup of viruses belonging to the the Bunyaviridae family, genus Orthobunyavirus. These serogroup viruses have mostly been found in ruminants in Asia, Australia, Africa and the Middle East. The Akabane virus has previously been reported in cattle in Turkey.

[1] The virus was provisionally named Schmallenberg after the German town where it was first identified.
[2] For the related Akabane virus, in sheep this stage is between 28 and 36 days of pregnancy and in cattle between 75 and 110 days.
[3] Bluetongue is a non-contagious infection transmitted by midge insects affecting domestic and wild ruminants including sheep, goats and deer.
[4] Shamonda-, Aino-, and Akabane-viruses